public class Check {
    public static void main(String[] args) {
        System.out.println(Person.classroom);//推荐通过类名进行访问
        Person per1=new Person();
        Person per2=new Person();
        System.out.println(per1.classroom);//不推荐通过对象进行访问
        System.out.println(per2.classroom);
    }
}
